In vitro regulation of FcepsilonRIalpha expression on human basophils by IgE antibody.
In vivo studies suggested the possibility of an IgE-dependent regulation of high-affinity (FcepsilonRI) IgE receptor expression on basophils. The current studies extend these observations to in vitro cultures of human basophils. Incubation of basophils for 3 to 4 weeks resulted in a slow dissociation of IgE antibody, during which time FcepsilonRI expression decreased, as measured by flow cytometry using the anti-FcepsilonRIalpha monoclonal antibody, 22E7, or by measuring FcRIalpha mass by Western blotting of whole-cell lysates. Culture of basophils with IgE resulted in upregulation of FcepsilonRIalpha expression by both flow cytometry and Western blotting of whole-cell lysates. Upregulation followed a linear time course during 2 weeks of culture. The relative increase in FcepsilonRIalpha density depended on the starting density; with starting densities of FcepsilonRIalpha of 10,000 to 170,000 per basophil, the upregulation varied 20- to 1.1-fold, respectively. Upregulation occurred in high-purity basophils, was not influenced by IgG at concentrations up to 1 mg/mL, and was inhibited by dimeric IgE. Heat-inactivated IgE was less effective and the monoclonal antibody CGP51901 that prevents IgE binding to FcepsilonRIalpha blocked the ability of IgE to induce upregulation. The dose-response curve for IgE-induced upregulation had an effective concentration50 of 230 ng/mL. Although the receptor through which IgE induces this upregulation is not yet known, several characteristics suggest that the upregulation is mediated by IgE interacting through FcepsilonRIalpha itself.
MacGlashan
D
D
Johns Hopkins Asthma and Allergy Center, Baltimore, MD 21224, USA.
McKenzie-White
J
J
Chichester
K
K
Bochner
B S
BS
Davis
F M
FM
Schroeder
J T
JT
Lichtenstein
L M
LM
D000911:Antibodies, Monoclonal; D001491:Basophils / Q000276:immunology*; D015153:Blotting, Western; D002478:Cells, Cultured; D019281:Dimerization; D015536:Down-Regulation; D005434:Flow Cytometry; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism / Q000494:pharmacology*; D007074:Immunoglobulin G / Q000494:pharmacology; D017455:Receptors, IgE / Q000378:metabolism*; D013997:Time Factors; D015854:Up-Regulation
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D017455:Receptors, IgE; D007073:Immunoglobulin E